The long-range goals of this project are to use polypyrrole-based anion receptors to understand the fundamental factors that regulate anion recognition and transport processes in biology and to develop synthetic systems that are useful in the diagnosis and treatment of human disease. This two-year project is concerned specifically with 1) the design of high- affinity receptors that will allow for anion recognition in the presence of water, especially those targeting chloride and phosphate, and 2) using these agents to create new polymeric systems with anion-specific recognition properties and demonstrating that these latter polymers may be used for the sequestration of phosphate and other anions under interfacial conditions. The focus will be on calixpyrrole and pyrrole-amide receptors that rely on multiple donor sets and which take advantage of new anion recognition motifs (e.g., CH-anion hydrogen bonds, localized charges,and ion-pairing interactions) and controlled geometries (achieved through strapping one receptor face, for instance) to achieve the requisite high affinity while still. Permitting functionalization and polymerization. The expectation is that by the time this two-year project is complete, a new set of polymerbased extractants will be in hand that could then be developed further for eventual use in the control of end-stage renal disease, where phosphate anion removal represents an important unsolved problem.